InAlN/GaN layers grown by metalorganic vapor phase epitaxy have been investigated by transmission electron
microscopy (TEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). It is shown that the surface
morphology and the crystallinity of the InAlN layers critically depend on the In composition. AFM analysis points out
that step flow growth may not be easily attained in this system: when the InAlN or AlN interlayer thickness is increased,
the growth mode becomes three dimensional. However, the formed islands are hundred of nanometers apart, and were
not observed in the transmission electron microscope. From the TEM investigation, it is pointed out that v-shaped
defects are present at the surface of some layers and they may be as deep as the whole ternary alloy, they are connected
to threading dislocations originated from the underlying template layers. As expected the measured residual strain is
minimum when the ternary layer composition is close to 16-17% In.